Fair Value Measurements (Quantitative Information About Level 3 Instruments) (Details) (USD $)	3 Months Ended
	Sep. 30, 2012
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Derivative Assets (Liabilities), at Fair Value, Net	$ 25,961,000
Income Approach Valuation Technique [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Derivative Assets (Liabilities), at Fair Value, Net	6,040,000
Fair Value Measurements Valuation Techniques	Discounted Cash Flow
Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Derivative Assets (Liabilities), at Fair Value, Net	$ 6,040,000
Tetco M1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Derivative Settlement Period Date Range Start	10/1/2012
Derivative Settlement Period Date Range End	12/31/2012
Tetco M1 [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Pricing Index	TETCO M1
Tetco M1 [Member] | Maximum [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Forward Pricing Range	3.55
Tetco M1 [Member] | Minimum [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Forward Pricing Range	2.92
Houston Ship Channel [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Derivative Settlement Period Date Range Start	10/1/2012
Derivative Settlement Period Date Range End	12/31/2012
Houston Ship Channel [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Pricing Index	Houston Ship Channel
Houston Ship Channel [Member] | Maximum [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Forward Pricing Range	3.56
Houston Ship Channel [Member] | Minimum [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Forward Pricing Range	2.98
Natural Gas Midcontinent [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Derivative Settlement Period Date Range Start	10/1/2012
Derivative Settlement Period Date Range End	12/31/2012
Natural Gas Midcontinent [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Pricing Index	Natural Gas – Midcontinent
Natural Gas Midcontinent [Member] | Maximum [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Forward Pricing Range	3.53
Natural Gas Midcontinent [Member] | Minimum [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Forward Pricing Range	2.77